<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <link rel="stylesheet" href="css/Span.css" type="text/css">

    <title>Title</title>
</head>
<body>
<p>剩余时间：<span id="countdown">60</span>秒</p>

<script src="script/Span.js">
    // 修改剩余时间为 30 秒
    // document.getElementById("countdown").textContent = "30";
</script>
</body>
</html>